// 添加到购物车
        protected void BtnAddToCart_Click(object sender, EventArgs e)
        {
            // 判断是否已经有用户登录
            if (Session["account"] == null)
            {
                Response.Redirect("Login.aspx");
                return;
            }
            int num = 0;

            try
            {
                num = Convert.ToInt32(BuyNumber.Text);
            }
            catch (Exception)
            {
                BuyNumber.Text = "0";
                return;
            }
            // 根据Session获取用户ID,进行商品的添加
            Account  account  = (Account)Session["account"];
            OrderDao orderDao = new OrderDao();

            // 添加到数据库
            if (orderDao.AddNewOrder(account.Id, BookId, num))
            {
                ErrorInfo.CssClass = "text-primary";
                ErrorInfo.Text     = "商品已经添加~";
            }
            else
            {
                ErrorInfo.Text = "加入购物车失败 = =";
            }
        }